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Environmental Geochemistry and Health Jun 2024In our previous study, the decontamination efficiency of cesium-137 (Cs) by Napier grass (Pennisetum purpureum Schum.) in the field was shown to be variable and often...
In our previous study, the decontamination efficiency of cesium-137 (Cs) by Napier grass (Pennisetum purpureum Schum.) in the field was shown to be variable and often influenced by natural environmental factors. To elucidate the factors influencing this variable Cs-decontamination efficiency, we investigated the influences of soil type and drought stress on Cs accumulation using cesium-133 (Cs) in Napier grass grown in plastic containers. The experiment was performed using two soil types (Soil A and B) and three different soil moisture conditions: well-watered control (CL), slight drought stress (SD), and moderate drought stress (MD). Overall, our results indicate that soil type and drought have a significant impact on plant growth and Cs accumulation in Napier grass. Plant height (PH), tiller number (TN), leaf width (W), and dry matter weight of aboveground parts (DW) and root parts (DW) in Soil B were greater than those in Soil A. Drought stress negatively affected chlorophyll fluorescence parameters (maximal quantum efficiency of photosystem (PS) II photochemistry and potential activity of PS II), PH, TN, W, DW, DW, and total Cs content (TCs), but it had a positive effect on Cs concentration. The Cs concentration in the aboveground parts (Cs) was increased by MD approximately 1.62-fold in Soil A and 1.11-fold in Soil B compared to each CL counterpart. The TCs in the aboveground parts (TCs) decreased due to drought by approximately 19.9%-39.0% in Soil A and 49.9%-62.7% in Soil B; however, there was no significant effect on TCs due to soil type. The results of this study indicate that soil moisture is a key factor in maintaining Napier grass Cs-decontamination efficiency.
Topics: Cesium Radioisotopes; Droughts; Soil Pollutants, Radioactive; Pennisetum; Soil
PubMed: 38849625
DOI: 10.1007/s10653-024-02023-1 -
The Plant Cell Jun 2024The photosynthetic apparatus is formed by thylakoid membrane-embedded multiprotein complexes that carry out linear electron transport in oxygenic photosynthesis. The...
The photosynthetic apparatus is formed by thylakoid membrane-embedded multiprotein complexes that carry out linear electron transport in oxygenic photosynthesis. The machinery is largely conserved from cyanobacteria to land plants, and structure and function of the protein complexes involved are relatively well studied. By contrast, how the machinery is assembled in thylakoid membranes remains poorly understood. The complexes participating in photosynthetic electron transfer are composed of many proteins, pigments and redox-active cofactors, whose temporally and spatially highly coordinated incorporation is essential to build functional mature complexes. Several proteins, jointly referred to as assembly factors, engage in the biogenesis of these complexes to bring the components together in a step-wise manner, in the right order and time. In this review, we focus on the biogenesis of the terminal protein supercomplex of the photosynthetic electron transport chain, photosystem I (PSI), in vascular plants. We summarize our current knowledge of the assembly process and the factors involved, and describe the challenges associated with resolving the assembly pathway in molecular detail.
PubMed: 38848316
DOI: 10.1093/plcell/koae169 -
Journal of the American Chemical Society Jun 2024Redox-inactive metal ions are essential in modulating the reactivity of various oxygen-containing metal complexes and metalloenzymes, including photosystem II (PSII)....
Redox-inactive metal ions are essential in modulating the reactivity of various oxygen-containing metal complexes and metalloenzymes, including photosystem II (PSII). The heart of this unique membrane-protein complex comprises the MnCaO cluster, in which the Ca ion acts as a critical cofactor in the splitting of water in PSII. However, there is still a lack of studies involving Ca-based reactive oxygen species (ROS) systems, and the exact nature of the interaction between the Ca center and ROS in PSII still generates intense debate. Here, harnessing a novel Ca-TEMPO complex supported by the β-diketiminate ligand to control the activation of O, we report the isolation and structural characterization of hitherto elusive Ca peroxides, a homometallic Ca hydroperoxide and a heterometallic Ca/K peroxide. Our studies indicate that the presence of K cations is a key factor controlling the outcome of the oxygenation reaction of the model Ca-TEMPO complex. Combining experimental observations with computational investigations, we also propose a mechanistic rationalization for the reaction outcomes. The designed approach demonstrates metal-TEMPO complexes as a versatile platform for O activation and advances the understanding of Ca/ROS systems.
PubMed: 38847558
DOI: 10.1021/jacs.4c00906 -
Seasonal variation in the relationship between leaf chlorophyll content and photosynthetic capacity.Plant, Cell & Environment Jun 2024Accurate estimation of photosynthesis is crucial for ecosystem carbon cycle modelling. Previous studies have established an empirical relationship between photosynthetic...
Accurate estimation of photosynthesis is crucial for ecosystem carbon cycle modelling. Previous studies have established an empirical relationship between photosynthetic capacity (maximum carboxylation rate, V; maximum electron transport rate, J) and leaf chlorophyll (Chl) content to infer global photosynthetic capacity. However, the basis for the Chl-V relationship remains unclear, which is further evidenced by the temporal variations in the Chl-V relationship. Using multiple years of observations of four deciduous tree species, we found that V and J acclimate to photosynthetically active radiation faster (4-8 weeks) than Chl (10-12 weeks). This mismatch in temporal scales causes seasonality in the V-Chl relationship. To account for the mismatch, we used a Chl fluorescence parameter (quantum yield of Photosystem II, Φ(II)) to tighten the relationship and found Φ(II) × Chl correlated with V and J (r = 0.74 and 0.72 respectively) better than only Chl (r = 0.7 and 0.6 respectively). It indicates that Φ(II) accounts for the short-term adjustment of leaf photosynthetic capacity to light, which was not captured by Chl. Our study advances our understanding of the ecophysiological basis for the empirical V-Chl relationship and how to better infer V from Chl and fluorescence, which guides large-scale photosynthesis simulations using remote sensing.
PubMed: 38847340
DOI: 10.1111/pce.14997 -
Journal of Photochemistry and... May 2024The deprotonation of O6 within the S state marks the final deprotonation event before the formation of oxygen‑oxygen bond interactions and eventual production and...
The deprotonation of O6 within the S state marks the final deprotonation event before the formation of oxygen‑oxygen bond interactions and eventual production and release of dioxygen. Gaining a thorough understanding of this event, from the proton acceptors involved, to the exfiltration pathways available, is key in determining the nature of the resulting oxygen species, influencing the mechanism through which the first oxygen‑oxygen bond forms. Computational analysis, using BS-DFT methodologies, showed that proton abstraction by the local Glu189 residue provides consistent evidence against this being a viable mechanistic pathway due to the lack of a stable product structure. In contrast, abstraction via W3 shows an increasingly stable oxo-oxo product state between r[O5O6] = 2.1 Å & 1.9 Å. The resulting oxo-oxo state is stabilised through donation of β electron character from O6 to Mn1 and α electron character from O6 to O5. This donation from the O6 lone pair is shown to be a key factor in stabilising the oxo-oxo state, in addition to showing the initiation of first O5-O6 bond.
PubMed: 38843709
DOI: 10.1016/j.jphotobiol.2024.112946 -
International Journal of Biological... Jun 2024Fructose 1,6-bisphosphate aldolase (FBA) is a pivotal enzyme, which plays a critical role in fixing CO through the process of in the Calvin cycle. In this study, a...
Fructose 1,6-bisphosphate aldolase (FBA) is a pivotal enzyme, which plays a critical role in fixing CO through the process of in the Calvin cycle. In this study, a comprehensive exploration of the FBA family genes in moso bamboo (Phyllostachys edulis) was conducted by the bioinformatics and biological analyses. A total of nine FBA genes (PeFBA1-PeFBA9) were identified in the moso bamboo genome. The expression patterns of PeFBAs across diverse tissues of moso bamboo suggested that they have multifaceted functionality. Notably, PeFBA8 might play an important role in regulating photosynthetic carbon metabolism. Co-expression and cis-element analyses demonstrated that PeFBA8 was regulated by a photosynthetic regulatory transcription factor (PeGLK1), which was confirmed by yeast one-hybrid and dual-luciferase assays. In-planta gene editing analysis revealed that the edited PeFBA8 mutants displayed compromised photosynthetic functionality, characterized by reduced electron transport rate and impaired photosystem I, leading to decreased photosynthesis rate overall, compared to the unedited control. The recombinant protein of PeFBA8 from prokaryotic expression exhibited enzymatic catalytic function. The findings suggest that the expression of PeFBA8 can affect photosynthetic efficiency of moso bamboo leaves, which underlines the potential of leveraging PeFBA8's regulatory mechanism to breed bamboo varieties with enhanced carbon fixation capability.
PubMed: 38838894
DOI: 10.1016/j.ijbiomac.2024.132885 -
Journal of Environmental Management Jun 2024The traditional homogenous and heterogenous Fenton reactions have frequently been restrained by the lower production of Fe ions, which significantly obstructs the...
The traditional homogenous and heterogenous Fenton reactions have frequently been restrained by the lower production of Fe ions, which significantly obstructs the generation of hydroxyl radicals from the decomposition of HO. Thus, we introduce novel photo-Fenton-assisted plasmonic heterojunctions by immobilizing FeO and Bi nanoparticles onto 3D SbO via co-precipitation and solvothermal approaches. The ternary SbO/FeO/Bi composites offered boosted photo-Fenton behavior with a metronidazole (MNZ) oxidation efficiency of 92% within 60 min. Among all composites, the SbO/FeO/Bi-5% hybrid exhibited an optimum photo-Fenton MNZ reaction constant of 0.03682 min, which is 5.03 and 2.39 times higher than pure SbO and SbO/FeO, respectively. The upgraded oxidation activity was connected to the complementary outcomes between the photo-Fenton behavior of SbO/FeO and the plasmonic effect of Bi NPs. The regular assembly of FeO and Bi NPs enhances the surface area and stability of SbO/FeO/Bi. Moreover, the limited absorption spectra of SbO were extended into solar radiation by the Fe defect of FeO NPs and the surface plasmon resonance (SPR) effect of Bi NPs. The photo-Fenton mechanism suggests that the co-existence of FeO/Bi NPs acts as electron acceptor/donor, respectively, which reduces recombination losses, prolongs the lifetime of photocarriers, and produces more reactive species, stimulating the overall photo-Fenton reactions. On the other hand, the photo-Fenton activity of MNZ antibiotics was optimized under different experimental conditions, including catalyst loading, solution pH, initial MNZ concentrations, anions, and real water environments. Besides, the trapping outcomes verified the vital participation of OH, h, and O in the MNZ destruction over SbO/FeO/Bi-5%. In summary, this work excites novel perspectives in developing boosted photosystems through integrating the photocatalysis power with both Fenton reactions and the SPR effects of plasmonic materials.
Topics: Oxidation-Reduction; Metronidazole; Hydrogen Peroxide; Surface Plasmon Resonance; Iron; Water Pollutants, Chemical; Antimony; Water
PubMed: 38838534
DOI: 10.1016/j.jenvman.2024.121347 -
Physiologia Plantarum 2024Heat stress substantially reduces tomato (Solanum lycopersicum) growth and yield globally, thereby jeopardizing food security. DnaJ proteins, constituents of the heat...
Heat stress substantially reduces tomato (Solanum lycopersicum) growth and yield globally, thereby jeopardizing food security. DnaJ proteins, constituents of the heat shock protein system, protect cells from diverse environmental stresses as HSP-70 molecular co-chaperones. In this study, we demonstrated that AdDjSKI, a serine-rich DnaJ III protein induced by pathogens, plays an important role in stabilizing photosystem II (PSII) in response to heat stress. Our results revealed that transplastomic tomato plants expressing the AdDjSKI gene exhibited increased levels of total soluble proteins, improved growth and chlorophyll content, reduced malondialdehyde (MDA) accumulation, and diminished PSII photoinhibition under elevated temperatures when compared with wild-type (WT) plants. Intriguingly, these transplastomic plants maintained higher levels of D1 protein under elevated temperatures compared with the WT plants, suggesting that overexpression of AdDjSKI in plastids is crucial for PSII protection, likely due to its chaperone activity. Furthermore, the transplastomic plants displayed lower accumulation of superoxide radical (O ) and HO, in comparison with the WT plants, plausibly attributed to higher superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities. This also coincides with an enhanced expression of corresponding genes, including SlCuZnSOD, SlFeSOD, SlAPX2, and SltAPX, under heat stress. Taken together, our findings reveal that chloroplastic expression of AdDjSKI in tomatoes plays a critical role in fruit yield, primarily through a combination of delayed senescence and stabilizing PSII under heat stress.
Topics: Solanum lycopersicum; Photosystem II Protein Complex; Heat-Shock Response; Fruit; Plant Proteins; Plant Leaves; Plastids; Chlorophyll; HSP40 Heat-Shock Proteins; Plants, Genetically Modified; Plant Senescence; Gene Expression Regulation, Plant; Malondialdehyde
PubMed: 38837422
DOI: 10.1111/ppl.14374 -
Nature Communications Jun 2024Classical photochemistry requires nanosecond excited-state lifetimes for diffusion-controlled reactions. Excited radicals with picosecond lifetimes have been implied by...
Classical photochemistry requires nanosecond excited-state lifetimes for diffusion-controlled reactions. Excited radicals with picosecond lifetimes have been implied by numerous photoredox studies, and controversy has arisen as to whether they can actually be catalytically active. We provide direct evidence for the elusive pre-association between radical ions and substrate molecules, enabling photoinduced electron transfer beyond the diffusion limit. A strategy based on two distinct light absorbers, mimicking the natural photosystems I and II, is used to generate excited radicals, unleashing extreme reduction power and activating C(sp)-Cl and C(sp)-F bonds. Our findings provide a long-sought mechanistic understanding for many previous synthetically-oriented works and permit more rational future photoredox reaction development. The newly developed excitation strategy pushes the current limits of reactions based on multi-photon excitation and very short-lived but highly redox active species.
PubMed: 38834625
DOI: 10.1038/s41467-024-49006-5 -
Plant Physiology Jun 2024Photomixotrophic growth A (PmgA) is a pleiotropic regulator essential for growth under photomixotrophic and prolonged high-light (HL) conditions in the cyanobacterium...
Photomixotrophic growth A (PmgA) is a pleiotropic regulator essential for growth under photomixotrophic and prolonged high-light (HL) conditions in the cyanobacterium Synechocystis sp. PCC 6803. The overall similarity with the anti-sigma factor of the bacterial partner-switching system indicates that PmgA exerts a regulatory function via phosphorylation of its target proteins. In this study, we performed an in vitro phosphorylation assay and protein-protein interaction analysis and found that PmgA interacts with four anti-sigma antagonist homologs, Ssr1600, Slr1856, Slr1859, and Slr1912, but specifically phosphorylates Ssr1600. Phenotypic analyses using the set of gene disruption and overexpression strains of pmgA and ssr1600 revealed that phosphorylation by PmgA is essential for the accumulation of Ssr1600 protein in vivo. The ssr1600-disrupted mutant showed similar phenotypes as those previously reported for the pmgA-disrupted mutant, namely, no obvious phenotype just after the shift to HL, but higher chlorophyll content, 5-aminolevulinic acid synthesis activity, and psaAB transcript levels than those in the wild-type after 6 hours. These findings indicate that the phosphorylated form of Ssr1600 works as the output of the partner-switching system to coordinately repress chlorophyll biosynthesis and accumulation of photosystem I during HL acclimation.
PubMed: 38833609
DOI: 10.1093/plphys/kiae323